If you walk down the automotive section of your nearest auto parts store you can find many products to add to your oil, your coolant, transmission fluid, fuel and steering systems, gear lube, and more. We are aware toes will be stepped on here when we say this, but for the most part, you want to stay far away from these oil additives. If your equipment manufacturer is calling for a specific additive to be used in, say, your coolant, then do so. If not, steer clear unless you have a serious problem with nothing to lose anyways, in which case you might get lucky. The only additives off the shelf generally considered “safe,” if not always effective, are fuel additives. There are good reasons why AMSOIL strongly recommends you refrain from pouring additives into your oils.

Engine and transmission oils arrive as a balanced chemical package straight out of the bottle. This is especially so with the highly formulated fluids AMSOIL engineers. When you pour in an aftermarket additive not designed to be used with your specific oil you drastically alter the chemical balance of that oil. Chemical balance (in addition to top quality additives and base stocks) is a big part of what makes our fluids excel not just in one area but in all areas simultaneously. It is very easy for inferior oils to perform well in one area at the expense of several others, but it's very difficult for an oil to excel in all areas at once, like AMSOIL does. Our white papers and field studies demonstrate this aptly. To emphasize the importance of this, AMSOIL will render null and void all product warranties if you use any aftermarket additive with our oils.In addition to disturbing your oil’s chemical balance, many aftermarket oil additives add chemicals that are harmful to your engine. There are two main types of oil additives used today which we’ll look at, as well as a third, less common type which is rather unique. There are others but they're not worth our time here. Look below the videos for details.

Chlorinated Additives

The first main class of oil additives contain chlorine, usually in the form of chlorinated paraffins. Many oil additives fall under this category. The reason companies use chlorine is that it’s a very cheap way to provide extreme pressure benefits. However, there are several significant problems with chlorinated oil additives. The first is that chlorine, which is a highly unstable and reactive element, quickly reacts with other elements and becomes caustic in an engine. Major oil companies removed chlorine from their products near the middle of the last century for this reason, and it's telling that aftermarket manufacturers don't list chlorine on the bottle as an active ingredient.

As oil begins to age in an engine its TBN (total base number) starts to deplete. While this is going on, the chlorine in these additives reacts with the water that naturally condenses inside your engine, esp. in the presence of catalytic wear metals, to produce hydrochloric acid. This is a very potent acid that rapidly neutralizes an oil's TBN, dramatically shortening the life of the oil. As the oil degrades further and its acid content increases, its ability to protect rapidly diminishes. Soon all TBN reserves will be lost, and once that happens the oil’s TAN (total acid number) will escalate rapidly. At this point there is nothing holding back the oil’s acidity, and its degradation will quickly snowball. Galling and spalling damage to engine components can start at this point, which will likely lead to catastrophic engine failure if not serviced in time.

One of the ironies of using chlorine as an extreme pressure additive in an engine oil is that, strictly speaking, most engines these days are not extreme pressure environments and don’t need this kind of protection. Most modern engines are low friction in general. Many valvetrains today use low friction rollers and cam followers, for example. Piston ring and cylinder bore wear is an area that needs more protection than other areas, but not from chlorine. Friction is often addressed by sliming down the rings, coating the bore with a protectant, or even reducing the number of rings from three to two. In older, high horsepower muscle cars with extra stiff valve springs and flat tappets, extra ZDDP protection is very beneficial in reducing wear, but chlorine is neither needed nor advised! There are too many risks associated with chlorine’s use.

What largely determines if a component is extreme pressure or not is the gear set used. Spur gears on an engine’s crank are not nearly as hard on oil as the hypoid gears found in a differential, for example. The teeth on hypoid gears transmit huge amounts of torque as they slide over each other in a sideways motion when they turn, and quickly shear inferior oils. Differentials need a lube with extreme pressure properties, but most engines do not. Chlorinated oil treatments alter the chemistry of your oil and the chlorine itself is a very dangerous chemical for your engine. Many people are suckered by slick marketing with these additives. Don’t be one of them.

We’ve included two relevant PDF’s below. One is a technical service bulletin AMSOIL issued a while back on this topic. A customer catastrophically destroyed the top end of his big diesel because he was using a chlorinated oil additive. He failed to change the oil quick enough, and the snowballing effects of rampant acid accumulation and oil degradation set in. No doubt he figured he was protecting his engine better when in fact he was the architect of its destruction! You have the golden opportunity to learn from his mistake.

The second PDF is a fluid analysis report from our partner lab. I had this same discussion with a customer who was using a very expensive aftermarket additive. He was reluctant to give it up even when he started using AMSOIL. He agreed to send a sample of new, unused oil additive to the lab and have it tested for chlorine content. The proof is in the pudding: the results came back with 130,000 ppm of chlorine in that additive.

The second main class of oil additive adds a chemical called Polytetrafluoroethylene (PTFE) into your engine where it coats components. It’s a low-friction coating. In essence it’s the same thing as Teflon, but don’t say that out loud because Teflon is a registered trademark. These types of products are suspended in what is usually a 50 weight petroleum base stock. Like everything else in life, there are pros and cons to using these additives that need to be weighed. What happens when you use these products is that you can get some initial and short-term anti-friction and mileage benefits when freshly installed for the first time before deposits can accumulate.

However. The cons are more serious and much longer lasting. The first is how short lived any possible benefits really are. If such coatings don’t last on your non-stick frying pan, they certainly won’t last in your engine where exposed to extremely high combustion temps and where hot metal parts are scraping against each other forcefully thousands of times each minute! Another is that PTFE is a non-discriminating “sticker.” It will stick to parts you don’t want it to. If PTFE can stick to a high temperature cylinder liner while being continually scuffed by the piston rings, as these additive manufacturer's claim, it stands to reason it will stick a lot easier to non-scuffing parts such as the oil pan, valvetrain and fine oil passageways.

Moreover, eventually PTFE will get scraped and/or burned off key friction points. It then has to go someplace. It can circulate through the oil system and partially clog small oil passageways, or solenoids for variable valve timing, for example, restricting oil flow and negatively affecting functionality. Or it can settle in places like the valve train or oil pan. It can also be pulled out of circulation by the oil filter, which uses up the filter's contaminant holding capacity. Moreover, by adding heavier weight fluids to your sump you are altering the viscosity of your oil. Many vehicles today call for 20 weight oil from the factory…pouring in a bottle of 50 weight additive is not helpful. Of course adding these chemicals into the sump will alter the chemistry of the oil, and lastly, some aftermarket additives can be very expensive!

Molybdenum Disulfide

Molybdenum Disulfide (Moly for short) is a relatively inert inorganic compound (MoS2) that is good at resisting thermal oxidation up to several hundred degrees Centigrade. It can be used as a dry lubricant, like graphite, when ground into fine particles of roughly 1-100 nano meters. If you could see it with your eyes, at those sizes it would appear like tiny “platelets” or sheets, loosely attached to and sliding over each other when sandwiched between moving parts, much like when a card shark slides or “spreads" a deck of cards open on a table. Moly platelets are more attracted to the metal surfaces in your engine than to each other, though they do have a weak attraction to each other as well, which gives them cohesion. They shift and slide around when “squished” between engine components, staying in overlapping contact with each other. So long as there is sufficient quantity, they form a malleable barrier between moving metal parts. It’s pretty cool.

Moly has a place as a lubricant. It is particularly well suited for use in heavy duty greases subject to heavy shearing loads. True, it has been used for decades by pilots in their older air cooled engines because it could help maintain (temporary) lubricity even if most of the engine oil accidentally leaked out: a very desirable trait for air personal! Even though Moly doesn’t upset the chemical balance of your oil nearly as much as other chemical additives or highly reactive chlorine, there are still considerations that discourage its use in engines.

Quality control is an important question. Not all manufacturers take the effort needed to process Moly correctly. If the particles are too large they are not as effective and secondly, they will get pulled out of circulation by the oil filter. This is a particular problem with AMSOIL’s full flow oil filters because they filter out smaller size particles more efficiently than any other filter on the market. This would deposit much of the Moly in your filter instead of in critical lubrication points and plug up your filter quicker as well.

In addition, Moly comes mixed with various base stocks that are much thicker than what most engines today require, altering the oil’s viscosity. These base stocks will always be inferior in quality to AMSOIL’s, which will dilute and weaken the benefits of our oils. Another consideration AMSOIL takes seriously is the issue of suspension. Moly cannot be kept in perfect suspension and does fall out and accumulate in various places. So while Moly is less disruptive to the chemistry of oils it is the official position of AMSOIL not to use any oil additives, including Moly, and for sound reasons. You can trust the expertise of AMSOIL here.

Concluding Thoughts

Even though a lot of people think they’re doing themselves a favour by using engine and drivetrain fluid additives, it doesn’t make sense to go cheap on oil in the first place and then spend a lot of money on a mismatched additive, or spend a lot on both for that matter. Aftermarket additives will very likely disrupt your oils chemistry & viscosity and score you questionable short-term benefits at best. Often you will gain no benefit at all, but suffer extra wear and risk serious long-term damage. There are too many problematic ingredients and unaccounted for variables and unknowns with aftermarket additives to make them a wise choice, and their use will void AMSOIL’s warranty.

We've learned that some people get pretty annoyed when told what they're doing to protect their equipment could actually be damaging it. We're not here to step on your toes, but to help inform. The desire to protect your equipment is not a bad thing; it's a sign of wisdom! However, thorough research into the matter reveals these additives, generally, are not worth the money or the major headaches that can come with their use. Save your money and your ride! Do it right the first time around. Use AMSOIL's premium fluids and you won't need extra additives, ever. You simply can't go wrong this way.